Why append to another ascii file, why not to a memo field in a table, then export that memo field to an ascii file, then Append FROM to your Table.

gnFileHandle = FOPEN("DataIn.TXT")
DO WHILE NOT feof(gnFileHandle)
 gcString = FGETS(gnFileHandle, 1060) && or LF+CR, which ever is first
 if NOT USED('MOVEtable')
  use movetable in 0 
 endif
 select movetable
 replace line1 with gcstring
ENDDO
=FCLOSE(gnFileHandle)
copy MEMO LINE1 to newfile.txt
if not USED('NewData')
 Use NewData in 0 
endif
select NewData
Append from Newfile.txt sdf